textproduct: Albany

WHAT HAS CHANGED

Some adjustments to hourly PoPs with the rain ending with the low pressure system and the approach of the cold front from eastern Great lakes Region and the St Lawrence River Valley with showers and t-storms late this pm/tonight. A Slight Risk (Level 2 of 5) was placed over a small area of the western Mohawk Valley with a Marginal Risk (Level 1 of 5) predominately north and west of the mid Hudson Valley, southern Taconics and NW CT.

Continued colder min temps Mon night/Tue morning, where some patchy to areas of frost are possible in the west/southwest Adirondacks and a Frost Advisory may be needed for Hamilton and and northern Herkimer Counties, if confidence increases for areas to widespread frost.

KEY MESSAGES

1) A cold front will bring isolated to scattered thunderstorms mainly areas north and west of the Capital Region and southern VT late this afternoon and into this evening. A few storms could be severe producing damaging winds and/or large hail.

2) It will be a mostly dry and cool start to the week with below normal temps before moderating above normal with the next chance of showers/t-storms late Wed into Thu.

DISCUSSION

KEY MESSAGE 1... The showers continue to exit the Berkshires and NW CT early this afternoon with the wave of low pressure and the mid level trough. The warm front never made it through and will wash out, as a cold front quickly approaches from the west. Cloud cover is abundant now, but has begun to thin over the western Dacks and western Mohawk Valley. The best SBCAPE on the SPC RAP Mesoanalysis is over these areas presently in the 500-1000 J/kg range. The latest 12Z HREFs continues to the show mean SBCAPEs 750-1250 J/kg mainly west of western New England late this afternoon into early tonight with lesser amounts over western New England in the 300-750 J/kg range. The clouds/lower stratus will have to clear quickly for destabilization to occur by the mid to late pm over eastern NY/western New England. The 0-6 km shear is 35-40 KT and slightly stronger upstream of the forecast area. Mid level lapse rates are relatively weak to marginal into tonight in the 5-6.5 C/km. However, a strong mid and upper level jet streak is approaching western NY and southeast Ontario by 00Z/Mon. Low-level moisture is still in place with dewpoints in the 60s and PWATS ranging 1.3-1.8" across the region. The cold front will be the focus for any thunderstorms. The CAMs continue to struggle with the coverage and extent of any strong to potentially severe thunderstorms. However, the latest 3-km HRRR/3-km NAM/WRF-ARW do have some discrete organized cells form into a cluster/broken line and approach the western Mohawk Valley/southwest Dacks and Schoharie Valley towards 23Z/7 pm and 01Z/9 pm and then weaken towards the Greater Capital Region/Lake George Saratoga Region/Taconics prior to midnight likely due to waning/lessening instability supporting taller updrafts.

SPC continues the Marginal Risk (Level 1 of 5) for most of the area north and west of the Mid-Hudson Valley/southern Taconics/NW CT and did upgrade a small area of the western Mohawk Valley (southern Herkimer/western Montgomery/northwest Schoharie) to Slight Risk (Level 2 of 5). Damaging winds would be the main threat especially with stronger winds aloft and the DCAPE values on some of the CAMS in these areas 750-1000 J/kg. Isolate severe hail is also possible in the Slight Risk area. The scattered showers and isolated to scattered thunderstorms will diminish between midnight to 3 am or so from northwest to southeast across the forecast area. It will become cool and breezy behind the front. Lows fall back into the 50s, except some mid and upper 40s over the southern Dacks, southern Greens and northern Catskills.

KEY MESSAGE 2... Strong cold advection occurs in the wake of the front through Monday morning. Deeper mixing and momentum transfer will allow for northwest winds 10-15 mph with some gusts 20-30 mph. The NBM/NBM90 winds/wind gusts were used for Monday. Temps were lowered slightly from the NBM closer to MAVMOS guidance with max temps running about 5 degrees or so below normal with upper 60s to lower 70s in the valleys and upper 50s to mid 60s over the higher terrain. The winds should diminish quickly in the late pm and early evening, as a sfc anticyclone moves over upstate NY and western New England. Clear skies and calm winds will promote ideal radiational cooling conditions with lows falling into the 30s and 40s. The mid and upper 30s will be mainly over the southern Dacks, upper Hudson Valley, southern Greens and northern Catskills, where patchy to localized areas of frost are possible. A frost advisory may be needed for Hamilton and northern Herkimer counties, if coverage and confidence increases for Mon Night/Tue morning.

Slightly below normal to seasonable temps and dry weather continues on Tuesday with the sfc high slowly retreating. Temps rise to near to slightly above normal readings by Wed. A cold front brings the next chance of showers and a few thunderstorms Wed night into Thu across eastern NY and western New England.

AVIATION /00Z MONDAY THROUGH FRIDAY/

A line of showers and thunderstorms associated with an approaching cold front. Although the general trend has been for this activity to be weakening, a shower or t-storm may impact KGFL and KALB over the next 1-2 hours. Within any shower or t-storm, a brief burst of heavy rainfall may allow for IFR visibility and gusty westerly winds. Otherwise, flying conditions will be VFR for these sites with bkn cigs around 3500 ft. KPSF may see a brief shower, but no thunder is expected there and the activity should be weak enough to keep flying conditions MVFR. The threat for any showers is very low for KPOU, so won't mention any shower or t-storms for that site.

Behind this activity, lingering bkn-ovc mid and high level clouds will stay in place for the rest of the overnight hours with VFR conditions and no additional precipitation. Light southerly winds will gradually become westerly at light speeds.

For Monday, flying conditions will be VFR with no precipitation. Skies will turn nearly completely clear and winds will be increasing. North to northwest winds will increase to 10 to 15 kts with some gusts in the 20 to 25 kt range. These winds will gradually decrease on Monday evening.

Outlook...

Monday Night: No Operational Impact. Patchy FG. Tuesday: No Operational Impact. NO SIG WX. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Moderate Operational Impact. Chance of SHRA. Thursday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Friday: Moderate Operational Impact. Chance of SHRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.